The present invention relates to a tire condition monitoring system for providing tire operation parameter information, such as tire inflation pressure, to a vehicle operator, and also relates to a vehicle keyless entry system, such as a passive keyless entry system for unlocking a vehicle door. The present invention relates specifically to a low-cost vehicle communication system that provides ready identification of a tire associated with the provision of condition information and avoids misidentification regardless of previous tire position change due to tire position rotation or the like.
Numerous tire condition monitoring systems have been developed in order to provide tire operation information to a vehicle operator. One example type of a tire condition monitoring system is a tire pressure monitoring system that detects when air pressure within a tire drops below a predetermined threshold pressure value.
There is an increasing need for the use of tire pressure monitoring systems due to the increasing use of xe2x80x9crun-flatxe2x80x9d tires for vehicles such as automobiles. A run-flat tire enables a vehicle to travel an extended distance after significant loss of air pressure within that tire. However, a vehicle operator may have difficulty recognizing the significant loss of air pressure within the tire because the loss of air pressure may cause little change in vehicle handling and little change in the visual appearance of the tire.
Typically, a tire pressure monitoring system includes a pressure sensing device, such as a pressure switch, an internal power source, and a communications link that provides the tire pressure information from a location at each tire to a central receiver. The central receiver is typically connected to an indicator or display located on a vehicle instrument panel.
The communications link between each tire and the central receiver is often a wireless link. In particular, radio frequency signals are utilized to transmit information from each of the tires to the central receiver. However, in order for the central receiver to be able to proper associate/identify received tire pressure information with the tire associated with the transmission, some form of identification of the origin of the signal must be utilized. A need for identification of the origin of the transmitted tire information signal becomes especially important subsequent to a tire position change, such as tire position rotation during routine maintenance.
One approach to identifying the origin of the transmitted tire information signal is to establish a communication link from the central receiver that controls or associates an identity with the transmissions from tires. Hardware components are needed that are capable of accomplishing such functions.
Passive or keyless vehicle entry systems are known. Such systems permit automatic unlocking of a vehicle door, or the like, for an authorized person wishing to gain entry into the vehicle. Specifically, the authorized person does not need to manually turn a key in a vehicle lock, manually actuate a hand-held transmitter, or manually input a code onto a vehicle touch pad.
A passive system includes an identification transceiver carried on the authorized person and a base transceiver located at the vehicle. The base transceiver interrogates the identification transceiver, and in response to the interrogation, the identification transceiver outputs a signal that conveys an appropriate identification or security code. In response to reception of the signal conveying the security code, the base transceiver unlocks the vehicle door. Thus, the authorized person may simply operate a door handle and open the door. Such systems are often referred to as contact-less identification and authentication systems.
In accordance with one aspect, the present invention provides a communication system for a vehicle. The system includes a portable identification device for keyless entry into the vehicle. The portable identification device includes means for receiving an interrogation signal and means for transmitting an identification indicative signal responsive to the interrogation signal. The system includes a tire sensor device for providing information regarding a condition at a tire of the vehicle. The tire sensor device includes means for sensing at least one tire condition, means for receiving an initiation signal, and means for transmitting a condition indicative signal responsive to the initiation signal. The system includes a transmitter arrangement for emitting the interrogation signal at a first frequency and the initiation signal at a second, different frequency. The transmitter arrangement includes at least one component that is operable for provision of both the interrogation signal at the first frequency and the initiation signal at the second frequency.
In accordance with another aspect, the present invention provides a communication method for a vehicle. At least one component is operated for transmission of an interrogation signal at a first frequency. The interrogation signal is received at a portable identification device for keyless entry into the vehicle. An identification indicative signal is transmitted from the portable identification device responsive to the interrogation signal. The at least one component is operated for transmission of an initiation signal at a second, different frequency. The initiation signal is received at a tire condition sensor device. A condition indicative signal, which is indicative of at least one sensed tire condition, is transmitted from the tire condition sensor device responsive to the initiation signal.